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Biomedical subjects

Y Masuda

Publications and source records attributed to Y Masuda.

At least 631 records · Page 35Linked to original sources
PubMed1990

Vascular pattern of the guinea pig tympanic membrane.

The vascular organization of the guinea pig tympanic membrane was studied by light microscopy in India-ink-, colored-gelatin-, or horseradish peroxidase (HRP)-injected specimens. The ultrastructural localization of the vessels was examined by transmission electron microscopy in HRP-injected material. We found that the tympanic membrane is supplied by two arterial sources, the superior and inferior tympanic arteries, both of which arise from the posterior auricular artery. The superior tympanic artery gives off arterioles which, in the tympanic membrane, run centrifugally from the attachment of the manubrium, while the inferior tympanic artery emits arterioles which run centripetally from the tympanic annulus. Both sets of arterioles divide into capillaries and form a monolayered polygonal meshwork. The capillaries drain into venules which run between arterioles in the membrane and empty into either the superior tympanic vein located at the manubrium or the inferior tympanic vein at the annulus.

Animals↗
PubMed1990

Coronary artery calcification detected by CT: clinical significance and angiographic correlates.

Cardiac computed tomography (CT) to detect coronary calcification was performed on 161 patients undergoing coronary angiography for proven or suspected coronary artery disease. Among 108 patients in whom coronary calcifications was identified, 90% had significant coronary stenosis angiographically (greater than 75% stenosis), and 80% of 121 patients with significant coronary stenosis showed calcification by CT. The relationship between the calcification site and the significance in stenosis of each vessel was determined. Calcification was present in 133 arteries among 205 stenotic coronary arteries (sensitivity = 65%) as compared with 59 of 439 entire arteries with normal coronary angiograms (specificity = 87%). In the younger age group the sensitivity of calcification for stenosis of each coronary artery was lower and the specificity and predictive value were generally higher than those in the elderly group. These results demonstrate that CT is a valuable procedure for detecting coronary arterial disease, since this examination is easy to conduct, noninvasive, and widely applicable for screening a large population.

Adult↗
PubMed1990

Assessment of relationship between the pattern of hypertrophy and the function of left ventricle in patients with chronic aortic regurgitation.

Pre- and postoperative echocardiograms of 64 patients with chronic aortic regurgitation who had undergone isolated aortic valvular replacement (AVR) were studied. These patients were divided into 3 groups as follows: (1) Group A patients who had preoperative end-diastolic radius to wall thickness ratio (R/Thd) less than or equal to 3. (2) Group B1 patients who had preoperative R/Thd greater than 3 and end-systolic radius to wall thickness ratio (R/Ths) less than 2. (3) Group B2 patients who had preoperative R/Thd greater than 3 and R/Ths greater than or equal to 2. Using this classification we assessed the relation between the pattern of hypertrophy and left ventricular (LV) function and the reversibility of LV dysfunction following AVR. Preoperatively, ejection fraction (EF) during handgrip exercise was unchanged in Group A (% delta EF: -2.8 +/- 7.1%) and significantly decreased in Groups B1 (-17.0 +/- 5.8%) and B2 (-20.2 +/- 4.6%). In the late postoperative period, however, it was, -1.2 +/- 3.3%, -2.0 +/- 4.6%, and -17.7 +/- 8.6% in Groups A, B1, B2, respectively. Preoperatively the slope of end-systolic wall stress/volume (ESWS-ESV relation was 1.96 +/- 0.43 in Group A (p less than 0.01 vs Group B2, NS vs Group B1), 1.54 +/- 0.38 in Group B1 (NS vs Group B2) and 1.17 +/- 0.47 in Group B2. It was stressed that a good relationship existed between the pattern of hypertrophy and function as well as the reversibility of LV dysfunction following AVR.

Adolescent↗
PubMed1990

Magnetic resonance imaging of the cardiovascular system: application in function and tissue characterization.

Magnetic resonance imaging (MRI) is a new noninvasive technique for visualization of the cardiovascular system, and is used to evaluate tissue characteristics, cardiac function and blood flow abnormalities, as well as to obtain morphological information. In this paper we presented results of clinical and laboratory research obtained using conventional spin echo MRI with regard to cardiovascular anatomy, tissue characterization and physiology. Furthermore, experience with two new techniques, cine-MRI and volume-selected MR spectroscopy, and their potential clinical usefulness in detecting cardiovascular diseases are documented.

Cardiovascular Diseases↗
PubMed1990

Action sites of antiallergic drugs on human neutrophils.

Sites of the inhibitory action of antiallergic drugs (azelastine, oxatomide, tranilast, repirinast and amlexanox) on human neutrophils were investigated by measuring leukotriene B4 formation, arachidonic acid release and superoxide generation. Results obtained in this study were as follows: (i) Formations of leukotriene B4 by neutrophils activated with a calcium ionophore (A23187) were effectively inhibited by all types of antiallergic drugs examined here, although the required concentrations were within a range of 20-200 microM. (ii) Releases of arachidonic acid from activated cells were diminished by azelastine and oxatomide that were classified as basic antiallergic drugs. On the contrary, acidic antiallergic agents including repirinast, amlexanox and tranilast enhanced the arachidonic acid liberation. (iii) Generations of superoxide from neutrophils activated with either phorbol 12-myristate 13-acetate or n-formyl-methionyl-leucyl-phenylalanine were effectively diminished only by the basic antiallergic drugs.

Arachidonic Acid↗
PubMed1990

Ultrastructures of the epithelial basement membrane and the subepithelial capillaries in rabbit palatine tonsils.

The ultrastructure of both the epithelial basement membrane and the subepithelial capillaries in rabbit tonsils was investigated using light and transmission electron microscopy of sections, and scanning electron microscopy of alkali-water macerated tissues. The basement membrane of the crypt epithelium was seen to consist of the lamina lucida, lamina densa and lamina fibroreticularis. The lamina fibroreticularis is made up of both fine and thick collagen fibrils. The basement membrane possesses numerous pores (0.5-20 microns in diameter) through which free cells migrate. The basement membrane overlying the follicle protrudes hemispherically towards the crypt lumen, while that over the interfollicular area forms many papillary projections. The capillaries are surrounded by collagen fibrillar sheaths invariably located below the collagen fibrillar sheet of the epithelial basement membrane. The capillaries immediately below the crypt epithelium, including switch-back loops of capillaries in the papillae, are fenestrated sinusoids (20-40 microns in diameter). Plasma cells, lymphocytes and macrophages are numerously gathered around the capillaries. Possible functional relations between these free cells and the fenestrated sinusoids are discussed.

Animals↗
PubMed1990

[Changes in systemic circulation under induced total spinal block and choice of vasopressors].

Total spinal block by using 2% lidocaine 0.5 ml.kg-1 (10.0 mg.kg-1) was carried out in adult mongrel dogs. The effects of atropine 0.02 mg.kg-1, isoproterenol 0.5 mcg.kg-1, methoxamine 0.1 mg.kg-1 and ephedrine 0.5 mg.kg-1 to counteract circulatory changes by total spinal block were studied. Atropine did not exert any marked influence on circulatory system. Isoproterenol elevated HR, LV dp/dt max and CI temporarily, but did not decrease MAP and SVR. Methoxamine elevated MAP and SVR, but decreased CI. Ephedrine is a drug of choice for this situation because it elevated HR, MAP, LV dp/dt max and SVR.

Anesthesia, Spinal↗
PubMed1990

[Progression to ischemic heart disease in subjects with coronary calcification as evaluated by computed tomography].

It is well known that coronary artery calcification develops in patients with advanced coronary sclerosis. Currently, it can be easily detected by computed tomography (CT). We studied the correlation of CT-detected coronary calcification with its progression to myocardial infarction, and further with the prognosis in various patients who did not have symptoms suggesting ischemic heart disease. The subjects consisted of 241 patients (136 males, 105 females) with a mean age of 61 years, categorized as a calcified coronary artery group (82 patients) and a non-calcified coronary artery group (159 patients). In all the subjects nonenhanced serial cardiac-CT scans were performed with a GECT/T 9800 for detecting coronary calcification. The mean follow-up period was four years in both groups. Among the 82 patients with coronary calcification, four developed myocardial infarction (4.9%) and 14 patients died (17%). Among the 159 patients without coronary calcification, none progressed to myocardial infarction, but 17 patients died unrelatedly (11%). Although there was no significant difference in mortality between the two groups, there was a statistical significance (p less than 0.005) as to the incidence of progression to myocardial infarction. In males, there was no significant difference (13 vs 12%) in mortality between the two groups, but the calcified group had a higher incidence of progression to myocardial infarction than that of the non-calcified group (5.5 vs 0%). In females, the calcified group had higher mortality (26 vs 8.9%) and a more frequent incidence of myocardial infarction (3.7 vs 0%) than did the non-calcified group. In conclusion, patients with coronary artery calcification are likely to develop coronary artery disease rather rapidly, even though asymptomatic. Therefore, detection of coronary calcification by non-enhanced CT is helpful for estimating the prognosis of coronary artery disease.

Calcinosis↗
PubMed1990

[Echocardiography in patients with malignant metastatic neoplasms of the heart and great vessels].

Two-dimensional echocardiography was used to study malignant metastatic neoplasms of the heart and great vessels in 20 patients, 13 males and seven females, whose ages ranged from 15 to 72 years. Five patients had lung cancer; two each had breast cancer, malignant melanoma, hepatoma and one each had gastric cancer, urinary bladder cancer, adrenocortical carcinoma, malignant lymphoma, angiosarcoma, fibrosarcoma, leiomyosarcoma; and two had cancers with unknown primaries. Tumor invasion was demonstrated echocardiographically in the left atrium in one each with breast cancer, fibrosarcoma and gastric cancer; in the right atrium in two with hepatomas; in the right atrium and right ventricle in one patient with adrenocortical carcinoma; in the left ventricle in one with lung cancer; and in the pulmonary artery in one with malignant melanoma. Massive pericardial effusion was observed in 11 of 20 patients; two with pericardial tumors including malignant lymphoma and lung cancer. We conjectured that metastatic tumors in the right cardiac cavities came through the inferior vena cava, and other tumors in the left atrium, left ventricle and pericardium developed from direct extension of the primary lesions. There was an 80% mortality of the patients during the observation period, and the average survival period after the diagnosis of cardiac metastases was 5.5 months. However, one patient was still living after two years of radiation therapy and chemotherapy. Echocardiography proved a useful, non-invasive means for the detection and follow-up observation of metastatic cardiac tumors.

Adolescent↗
PubMed1990

[Intra-operative pelvic hyperthermochemotherapy combined with surgery in rectal cancer].

In order to prevent local recurrence after curative surgery for rectal cancer, intra-operative pelvic hyperthermochemotherapy (IOPHC) was performed, combined with surgery. Nineteen patients with rectal cancer were given IOPHC (IOPHC group) and 25 patients who underwent curative surgery without IOPHC served as control, in the same period of time. IOPHC was done as follows: After rectal amputation or resection combined with extended lymphadenectomy, the pelvic cavity was filled with a prewarmed perfusate (physiological saline) containing 40 micrograms/ml of MMC. Then, an apparatus for IOPHC we devised was submerged in the perfusate to warm and maintain it at 45 degrees C for 90 minutes. The mean temperature of the esophagus was 37.2 degrees C, so it was not necessary to cool down the body throughout IOPHC. There was no significant postoperative morbidity between the two groups except that the total amount of exudate drained from pelvic cavity was larger in the IOPHC group. Local recurrence occurred in 3 controls, but in only one of the IOPHC group. Thus, IOPHC is a safe and reliable approach to prevent local recurrence of rectal cancer.

Adult↗
PubMed1990

[Effect of epidural anesthesia on the function of hormonal regulation in the hypothalamic-pituitary-testicular axis].

To evaluate the effects of epidural anesthesia on the hypothalamic-pituitary-testicular axis, we examined the concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH) and testosterone (T). The effects of epidural anesthesia on plasma levels of LH, FSH and T were investigated in 8 men aged from 64 to 87 years, suffering from untreated prostate cancer. There were no significant differences in plasma levels of LH, FSH or T between patients under epidural anesthesia and patients under no anesthesia. The effects of epidural anesthesia on plasma levels of LH, FSH and T after LH releasing hormone (LH-RH) administration were studied in 10 men between 65 and 84 years with diagnoses of untreated prostate cancer. Plasma LH and FSH levels increased significantly after LH-RH administration under epidural anesthesia or no anesthesia. Plasma LH and FSH were lower under epidural anesthesia than under no anesthesia. No change in plasma T level was observed after LH-RH administration under epidural anesthesia. We conclude that there is no effect of epidural anesthesia on the hypothalamic-pituitary-testicular axis.

Aged↗
PubMed1990

[Changes in systemic circulation and organ blood flow during induced total spinal block].

Total spinal block with lidocaine was performed in adult mongrel dogs, and circulatory changes or changes in organ blood flow were investigated. Dogs were divided into group A (5.1 mg.kg-1) and group B (10.0 mg.kg-1) according to the dose of lidocaine. During total spinal block, HR (79% and 78%), MAP (64% and 69%), LV dp/dt max (58% and 49%) and CI (67% and 67%) decreased significantly compared with the control values in groups A and B respectively. However, SVR was unchanged. The circulatory change occurred more rapidly in group B. Organ blood flow was measured in group A. Blood flow was measured in four areas during total spinal block. It was significantly decreased at liver and slightly decreased at cerebral cortex and medullary substance. However, renal cortex blood flow was not altered.

Anesthesia, Spinal↗
PubMed1990

[Measurement of myocardial blood flow using N-13 ammonia dynamic PET-theory and methodology].

Positron emission tomography (PET) offers the potential capability of noninvasive measurement of regional myocardial blood flow (RMBF) in man. Because N-13 ammonia exhibits properties which to some extent resemble those of the radioactive microsphere, we developed a first-pass flow method for noninvasive measurement of RMBF. In the present method, RMBF was determined by dividing myocardial activity at time T by arterial input integrated from the injection start to that time, where time T is the endpoint of first circulation of N-13 ammonia. Also in the present method a time-activity curve of left atrium was used as the arterial input function to make the procedure totally noninvasive. To validate the present method, we compared it with the compartment analysis. 5 patients with hypertrophic cardiomyopathy (HCM) and with a considerably thickened ventricular wall, were selected for the comparison between the first-pass flow method and the compartment analysis. The relationship of RMBFs by the two methods was y = 1.8 + 1.097x-0.002037x2 (n = 30, SEE = 5.5), where x (ml/min/100 g) was obtained by the compartment analysis, while y (ml/min/100 g) by the first-pass flow method. The result indicated that both were almost identical in physiological flow range (less than 100 ml/min/100 g), but that the first-pass flow method underestimated RMBF in the higher flow range due to venous leakage of N-13 ammonia. As the conclusion, we could at least measure RMBF of HCM patient in the physiological flow range by the present method. The future extension of the method was discussed.

Ammonia↗
PubMed1990

[Anesthetic management of a patient with osteogenesis imperfecta congenita].

We experienced anesthetic management of three cases of osteogenesis imperfecta. Case 1: A 2-year-old boy weighing 8.6 kg was premedicated with chloral hydrate 250 mg intrarectally, but he was very excited on arrival at the operating room. Induction of anesthesia was performed by intramuscular injection of ketamine 40 mg. Case 2: A 4-year-old girl underwent three surgeries (2 osteomies and 1 intramedullary nailing of the tibias) during the past two years. On the second and third procedures, marked hyperthermia (over 39.2 degrees C as rectal temperature) developed during halothane (1-2%) and enflurane (1.5-2.5%) anesthesia. However, on the first surgery, hyperthermia did not occur under combined light halothane (0.3-0.5%) anesthesia with caudal epidural block. Case 3: A 14-year-old female underwent osteotomy of the radius under brachial plexus block without any anesthetic complications. In conclusion, anesthetic considerations for children with this disease are as follows; 1) It is necessary to premedicate to provide good preoperative sedation. 2) Care should be taken to use inhaled anesthetic agents (halothane and enflurane) because of tendency to develop abnormal hyperthermia. 3) It is desirable to use regional anesthesia.

Adolescent↗
PubMed1990

[PET assessment of myocardial viability with glucose loading and fasting FDG images].

Positron emission tomography (PET) offers the potential capability of evaluating tissue viability. We have studied the changes of myocardial F-18 deoxyglucose (FDG) uptake with glucose loading. In a fasting state (for at least 5 hours) and in a glucose loading state (50 g glucose orally one hour before the study) FDG (74-148 MBq) PET studies were performed for 50-60 minutes in 3 cases. 2 were subjects with anterior myocardial infarction (MI) including one with a ventricular aneurysm (case 1), one with a recent MI (case 2). One was a subject of aortic valvular disease without coronary lesions (case 3). Arterial input function (Ca(t)) and myocardial activity (Cm(t)) were derived from the regions of interest (ROI) on the left atrium and from multiple ROI's circumferentially about the myocardium. Net extraction, FU (Fractional Uptake) = Cm(T)/integral of T0 Ca(t)dt, were calculated. Normal segment (N) showed an increase in FU with glucose loading, but the ischemic segment showed no increase (case 1) or a lower increase (case 2) relative to N. This study shows that the increase in FU with glucose loading suggests the persistence of viable myocardium. In conclusion, myocardial viability may be evaluated by comparing FDG images in a glucose loading state with those in a fasting state.

Adult↗